After numerous questions as to whether Osama BL was still alive, Osama himself decided to send a personal letter to George Bush to remind him he was still in the game.
George opened it to find a single line of coded message - 370H-SSV-0773H. He couldn't understand it so he emailed it to Condoleeza Rice. Condi and her aides hadn't a clue so she sent it to the FBI. No one could solve it there and they sent it on to the CIA, Australian Intelligence (ASIO) and Mossad who all drew a blank.
In desperation he sent it to M16 who replied a few minutes later - tell the President he's reading it upside down.